The present invention relates to compact fluorescent lamp systems. It finds particular application in conjunction with extending the life of a ballast unit within a compact fluorescent lamp system operated within an enclosed environment and will be described with particular reference thereto. It will be appreciated, however, that the invention will also find application in extending the life of ballast units in other types of fluorescent lamp systems.
In general, compact fluorescent lamps are manufactured as either integral or plug-in type systems. Both types of compact fluorescent lamp systems require the use of a ballast unit in conjunction with a lamp. Lamps in integral type systems are permanently connected to the ballast unit. Lamps in plug-in type systems, on the other hand, are removably connected to an external ballast unit. When either the lamp or the ballast unit in an integral type system reaches the end of its life, the entire system of lamp and ballast unit must be discarded. However, when a lamp in a plug-in type system expires, the lamp may simply be replaced. In either case, it is desirable that the ballast unit have a longer life than the lamp in order to insure the rated lamp life will be achieved.
The life of the ballast unit is often limited by the life of one of its most susceptible components (i.e., an electrolytic capacitor). The life of the electrolytic capacitor is a strong function of the temperature at which it operates. More specifically, the life of the electrolytic capacitor is lessened when it is operated at elevated temperatures. The electrolytic capacitor itself does not generate much heat while the fluorescent lamp system is operating. However, the fluorescent lamp and many of the other components within the ballast unit do not run as cool as the electrolytic capacitor. Therefore, heat generated by the lamp and these other component parts of the ballast unit tend to externally raise the temperature at which the electrolytic capacitor operates. Therefore, the heat generated by the operation of the lamp can negatively affect the life of the electrolytic capacitor and, consequently, the operation and life of the ballast unit. Conversely, it becomes apparent that operating the electrolytic capacitor at a lower temperature lengthens the life span of the ballast unit, particularly when the limiting factor is the electrolytic capacitor itself.
Fluorescent lamp systems have traditionally been manufactured using linear lamps electrically connected to a remote ballast unit and then installed in a fixture. Ballast units used with linear fluorescent lamp systems have a significant amount of their surface areas exposed to a relatively cool ambient air. Therefore, heat generated in these ballast units used with linear fluorescent lamps is more easily dissipated so that the ballast unit, and its electrolytic capacitor within the ballast unit, run substantially cooler. As described above, cooler running ballast units typically have longer life spans. In fact, the life span of a ballast unit used with a linear fluorescent lamp operated in normal application environments can be in the order of 100,000 hours. As contrasted, the life span of the lamp used in a linear system operated in typical environment is traditionally much shorter than that of the ballast unit. Therefore, the life span of the linear fluorescent lamp system is typically limited by the life of the lamp.
It is frequently desirable to operate fluorescent lamp systems in an enclosed environment. Because the system is not exposed to as much circulating cool air when it is used under such conditions, less heat is dissipated by convection and conduction, thereby raising the operating temperature of the ballast unit and shortening its life. For example, the life of the ballast unit used with a linear fluorescent lamp operating in an enclosed environment is reduced from approximately 100,000 hours to approximately 60,000 hours. Although this can represent a significant reduction in the life of that ballast unit, the life span of the ballast unit is still much longer than that of the lamp so that the system life is still determined by the life of the fluorescent lamp.
In order for compact fluorescent lamps operating in an open environment to deliver a life rating of 10,000 hours, the associated ballast unit life typically must be about 40,000 hours. Therefore, as in linear fluorescent lamp systems, it is desirable that the life span of a ballast unit used with a compact fluorescent lamp operating in any environment be much longer than the life span of that lamp.
A noticeable decrease in the life span of a ballast unit occurs in compact fluorescent lamp systems operated in an enclosed environment and, consequently, at elevated temperatures. More specifically, the life of the ballast unit in integral compact fluorescent lamp systems operated in an enclosed environment may be as short as 3,000 hours to 5,000 hours. Therefore, it is not uncommon for the life of ballast units in integral compact fluorescent lamp systems to be shorter than the life span of the lamp itself. As stated above, such a condition is grossly undesirable.
The inherent compressed design of the integral compact fluorescent lamp system makes it difficult to operate an enclosed ballast unit at lower, more desirable temperature conditions because of the stagnant air atmosphere surrounding the enclosed ballast unit assembly. Consequently, it is difficult to achieve the rated life of the ballast unit used within a compact fluorescent lamp, and functioning in an enclosed environment.
It is possible to incorporate electrolytic capacitors which have longer lives even when they operate at higher system ambient temperatures. However, these electrolytic capacitors are more expensive than traditional capacitors and, therefore, substantially increase the manufacturing cost of the assembled ballast unit used with the compact fluorescent lamp.
The present invention discloses a unique approach to achieve the improved performance and describes the technical explanation of how this new device overcomes the above-referenced problems and others.